1. Field of the Invention
This invention relates to annular scrapers and to shaft seals using scrapers and also to methods for making the same.
2. Description of the Prior Art
Scrapers and seals with scrapers are known, however, such prior devices using a brass scraper were of the assembled type mechanically held together, such as by a turned edge of a shell, as contrasted to the bonded construction of the present seal. Further, such prior art brass scrapers had slits (or splits) therein to attempt to afford some degree of flexibility, and they required a plurality of such brass scrapers to overlap the slits. However, such slits did afford a path for contaminants to enter the application and the overlapping was not completely successful in eliminating such paths. In addition, in control cables such as used on large bulldozers and other similar equipment there is a certain amount of cable deflection and previous scrapers could not handle this amount of deflection but would be permanently deformed allowing foreign contaminants to pass into the application.
It is an object of the present invention to provide an improved scraper, seal and method for making the same which overcomes the problems in the prior art. It is a further object of the present invention to provide a scraper with a backup ring of resilient elastomeric material, which scraper can repeatedly resiliently accommodate the encountered amount of cable deflection and return to its original position without losing the scraping function. It is a still further object of the present invention to provide in combination with such a scraper a functional polytetrafluoroethylene sealing element with a sealing lip. It is another object of the invention to provide a scraper having a continuous, uniform scraping edge without the slits of the prior art. It is another object of this invention to provide a method for making a scraper, and a seal with a scraper, which eliminates a separate piercing step, which also provides improved concentricity of the scraping edge, which also provides a bonded construction, and which eliminates a leakage path around the outside of the scraper. It is still another object of this invention to provide a cable control type of seal with a scraper and a bushing which guides the shaft in near perfect alignment.